The sun left the bright horizon of the Pacific Ocean long ago. Only the moon lightens up the surface of the ocean with a depth of 4.000m. Now the big moment for Abyss has come. Every two or three nights the AUV dives into a 16-hours-adventure.

It’s already dive Nr. 17, which is a new record within one expedition. The AUV now starts with a newly developed camera system, which we use for the first time, so our enthusiasm is huge. The system works fine and takes a lot of good pictures, which is a great validation for the long time of development.

The predive-check was successful, so we’re getting started! We open the doors of the container and the AUV shows up. Now it has to be pulled out of the container by us AUV-Engineers into the LARS (Launch and Recovery System). After one more final check of the camera system and the LED-Segment Abyss is finally ready to dive.

The bridge informs us, when we reached our position. Then, the team leader lifts up his thumbs, the LARS lifts up the AUV and lets it down slowly into the water by its hydraulic system. The AUV must be maneuvered manually after being released from the LARS, until there is a security distance to the ship. The mission starts as soon as this distance is reached. Abyss uses the power of its propeller and its fins to dive down in a few seconds. Now the vehicle works autonomous without any cable connection to the ship, which is a huge advantage, because other gears can be used in the meantime.

After 14 hours alone in the darkness the batteries of the AUV are almost empty, thus it is time to come „home“. After two more hours Abyss reaches the surface, sending us its position for recovery. With a LED-Flash the AUV shows where we can pick up the vehicle. The recovery always takes place at the starboard side. Via WLAN we release the Pick-Up-Float and the crew tries to catch the float with a throwing-hook, which has a hit-rate of almost 100 percent. After the float is picked up on deck, the AUV will be connected with the LARS, which pulls the vehicle up again. Then a small cleaning session follows, so the AUV can get back into the container.

The time between the pop up and the recovery is not so easy to manage for the chief scientist. He always has to minimize the timeslot to prevent a big drift of the AUV. It’s a big challenge because other gears are used in the same time.After the dive the camera of the AUV and other sensors show what happened on the seafloor. Abyss already covered during this cruise a region of around 1153 km. The pictures are taken 7.5 m above the seafloor and there is a lot to be discovered: sea urchins, sea cucumbers, sponges, shrimps and above all manganese nodules. Thus, these discoveries make all the scientists on board very happy. So far, this was the tenth dive with the new camera on this cruise with an amount of 193.309 pictures.

But now the batteries of the AUV have to be charged quickly, because the next dive into the darkness is already planned.